1. Field of the Invention
The present invention relates to refrigerated contain having self-contained refrigeration systems. Even more particularly, the present invention relates to an improved portable self-contained cooler/freezer apparatus wherein either an external bulk supply or self-contained carbon dioxide canister dispense CO.sub.2 or like liquid coolant through a manifold and plate like diffuse system to regulate temperature within the container, and wherein a temperature controlled solenoid valve dispenses CO.sub.2 or like coolant as needed into the shipping container walls to cool.
2. General Background
Many truck lines use refrigerated trucks to carry food products over long distances. Typically, such a truck is designed to carry either frozen foods or foods that must be maintained in higher, but still refrigerated temperatures, such as, for example, 40.degree. F. These trucks typically carry either refrigerated or frozen food only and differ from the typical common carrier truck which is unrefrigerated and which carries any of a number of bulk, unrefrigerated commodities, such as palletized loads of any general merchandise, product, or equipment. Presently, there does not exist a means for carrying refrigerated and/or frozen food products over long distances of several hundred or even thousands of miles via common carrier, namely, with trucks that are not refrigerated but which have space for holding any number of general commodities.
Several devices have been patented which have attempted to provide portable refrigeration devices. An example is U.S. Pat. No. 3,633,381, entitled "Open-Cycle Portable Refrigerator." In that patent there is disclosed a portable refrigerator employing an open cycle system. A stored compressed gas, such as carbon dioxide is passed from the storage container through an evaporator which comprises a serpentine passageway for the gas in a surrounding medium, such as water, an aqueous solution, which is maintained frozen due to the passage of the expanding compressed gas through the coiled passageway. The temperature of the evaporated medium is lower than the ambient temperature of the interior or the container comprising the storage portion of the refrigerator which is cooled thereby. The gas passing through the evaporator may be exhausted into the interior of the container whereby the cooler air which is, next to the evaporator medium is circulated throughout the interior of the container.
A portable ice chest having a refrigeration unit is disclosed in U.S. Pat. No. 3,959,982. A substantially closed refrigeration receptacle in fluid communication with the outlet side of the primary evaporator receives the refrigerant which may not have completely evaporated, and separates the phases by venting the evaporated gas phase to the atmosphere while directing the unevaporated liquid refrigerant into a second evaporated coil wherein it is completely evaporated. The thermostatically controlled valve regulates the flow of refrigerant to the primary evaporator as a function of temperature within the chest.
Several systems have been patented which use liquid carbon dioxide as part of a refrigeration system. Notice for example, U.S. Pat. No. 4,399,658, entitled "Refrigeration System With Carbon Dioxide Injector," issued to Nielsen; U.S. Pat. No. 4,459,825, entitled "Apparatus For Controlled Reduction In Temperature and Preservation Of Embryos In A Cryogenic State," issued to Crouch; and U.S. Pat. No. 4,580,411, entitled "Liquid Nitrogen Freezer," issued to James Orfitelli.
Several patents have been issued which relate to shipping containers that have, in some cases, self-contained refrigeration systems. Examples of these shipping containers include U.S. Pat. No. 3,961,925, issued to Rhoad; U.S. Pat. No. 4,502,293, issued to Franklin; U.S. Pat. No. 4,576,017, issued to Combs et al.; and U.S. Pat. No. 4,606,195, issued to Winkler.
The Rhoad U.S. Pat. No. 3,961,925 provides a portable self-contained refrigerated storage and transportation container for preserving perishable commodities and includes an insulated storage chamber for perishable commodities. A recirculating liquid cooling system is provided within the container and includes conduit and nozzle means disposed within the storage chamber adapted to spray a liquid coolant, such as chilled brine directly onto the perishable commodities to maintain them in a uniform cooled temperature. The sprayed liquid coolant is collected in the bottom portion of the storage chamber. A closed refrigeration system is also provided within the container and includes in part heat exchange means disposed within the bottom portion of the storage chamber for cooling the sprayed liquid coolant which has collected there.
The Franklin U.S. Pat. No. 4,502,293, entitled "Container CO.sub.2 Cooling System," provides a generally rectangular container that includes an insulated top, bottom, opposite sides and opposite end walls. An upstanding transverse insulated hollow housing is mounted within the container adjacent one end thereof and a CO.sub.2 snow cabinet constructed of good heat transfer material is disposed within the housing with opposing wall portions of the cabinet and housing passing exteriorly about the cabinet. A heat insulative horizontal baffle is mounted within the container spaced below the top wall and extends between the sidewalls thereof. The baffle defines a cooled air passage beneath the top wall extending lengthwise of the container. The airflow passage includes an outlet end adjacent and in at least reasonably closed communication with the end of the cooled air passage adjacent the aforementioned one container end wall and an inlet end opening outwardly of the housing into the interior of the container below the baffle. The end of the cooled air passage adjacent the other container end wall opens into the interior of the container and thermostatically controllable air pump structure is provided to effect airflow inwardly of the inlet of the airflow passage, through the airflow passage and into the cooled air passage. Further, structure is provided for spray discharging of liquid CO.sub.2 into the interior of the upper portion of the cabinet and into the airflow passage at points spaced therealong in order to form CO.sub.2 snow therein.
The Combs U.S. Pat. No. 4,576,017, discloses a container for maintaining its contents at a desired temperature for an extended period of time, such as for use in shipping contents in a frozen condition. The container includes an outer shell which is substantially air tight and which has an inner surface, a pass of heat exchange medium, a support structure for the heat exchange medium, and means for maintaining an air space between the contents of the container and substantially the entire inner surface of the outer shell of the container and between the contents of the container and the support structure for the heat exchange medium for allowing convection current to develop in the inner space which circulates past the heat exchange medium and maintains a substantially uniform temperature around the contents of the container.
In the Winkler U.S. Pat. No. 4,606,195, entitled "Hypobarric Container," there is provided a storage device having a walled inner and outer container and a compressed gas supply contained within the device. A conduit is provided from the gas supply to the inner container and a control valve for the conduit responsive to pressures above and below a super atmospheric pressure value are provided for closing and opening the valve.